An unknown word model for a generic language. This was originally designed for
German, changing only to remove German-specific numeric features. Models unknown
words based on their prefix and suffixes, as well as capital letters.

tagHash

This maps from a tag (as a label) to a Counter from word signatures to
their P(sig|tag), as estimated in the model. For Chinese, the word
signature is just the first character or its unicode type for things
that aren't Chinese characters.

getUnknownLevel

Get the level of equivalence classing for the model.
One unknown word model may allow different options to be set; for example,
several models of unknown words for a given language could be included in one
class. The unknown level can be queried with this method.